Vladimir Demikhov was a Russian surgeon who conducted some bizarre experiments.
In 1959 he successfully managed to surgically transplant the head of one dog onto another dog, effectively creating a two-headed dog!
He created about 20 two-headed dogs in 15 years.
Sadly the dogs didn't live for long after this, the longest one of these two-headed dogs lived for was about 1 month.
While this may sound like a crazy thing to do, his experiments helped pave the way for human organ transplants.